Pay what you want and get Psychonauts, Limbo, Superbrothers : Sword & Sworcery, and Amnesia : The Dark Descent (and Bastion, if you pay more than the average, which is currently $7.70.) Some of the money goes to charity.

...and now it also includes Lone Survivor, Braid and Super Meat Boy if you pay more than the average, (currently $8.32). Four days left to go.